Influence of ultrasound pretreatment on the subsequent glycation of dietary proteins

Hemoglobin-derived amyloid fibrils: Fibrillization mechanisms and potential applications

Fibrils from food proteins were widely reported but it has not been reported on sus scrofa hemoglobin. Utilizing fibrillization strategies can efficiently utilize hemoglobin and reduce waste. This work explores a new strategy to prepare hemoglobin-derived fibrils by removing the heme group. Hydrophobic interaction was found to be a key factor in promoting the fibrillization process. Heme presence hindered the fibrillization process possibly by restricting the unfolding process due to its high hydrophobicity. The core sequences of fibrils were identified as HBA 30-36, HBA 96-110, HBA 126-139, HBB 15-41, HBB 104-117 and HBB 83-145, which are generally of high hydrophobicity and HSA (Hot spots of aggregation) scores. Fibrils exhibited excellent gel properties, water retention, iron-binding properties, and enhanced positive surface charge. These findings contribute to establishing a fibrillization mechanism of hemoglobin and highlight the possibility of hemoglobin-sourced fibrils in food industry.

Emerging technologies in reducing dietary advanced glycation end products in ultra-processed foods: Formation, health risks, and innovative mitigation strategies

The widespread consumption of ultra-processed foods (UPFs) results from industrialization and globalization, with their elevated content of sugar, fat, salt, and additives, alongside the formation of dietary advanced glycation end products (AGEs), generating considerable health risks. These risks include an increased incidence of diabetes, cardiovascular diseases, and neurodegenerative disorders. This review explores the mechanisms of AGE formation in UPFs and evaluates emerging technologies and additives aimed at mitigating these risks. Both thermal methods (air frying, low-temperature vacuum heating, microwave heating, and infrared heating) and non-thermal techniques (high-pressure processing, pulsed electric fields, ultrasound, and cold plasma) are discussed for their potential in AGE reduction. Additionally, the review evaluates the efficacy of exogenous additives, including amino acids, polysaccharides, phenolic compounds, and nanomaterials, in inhibiting AGE formation, though results may vary depending on the specific additive and food matrix. The findings demonstrate the promise of these technologies and additives for reducing AGEs, potentially contributing to healthier food processing practices and the promotion of improved public health outcomes.

Structural and functional impacts of glycosylation-induced modifications in rabbit myofibrillar proteins

Rabbit meat, recognized for its nutritional value, is gaining global attention. However, the inferior functional properties of rabbit myofibrillar proteins lead to quality degradation during the production process. Glycosylation represents an effective method for enhancing protein functionality. This study investigated the glycosylation modification of rabbit myofibrillar proteins. The results demonstrated that solubility of glucose-glycosylated products increased by 34 %, while the reduction capacity improved from 0.15 mg/mL to 1.6 mg/mL. The·OH free radical scavenging ability increased from 63.94 % to 94.21 %. β-Glucan-glycosylated products exhibited the highest thermal stability, and their DPPH free radical scavenging rate increased from 19.68 % to 76.21 %. Glycosylation also induced changes in protein conformation, characterized by a 10-30 °C increase in thermal denaturation peak temperature, gradual attenuation of endogenous fluorescence intensity, gradual enhancement of λmax redshift, and a 30-40 % decrease in surface hydrophobicity. Molecular docking simulations revealed that the primary interactions between glucose, lactose, and β-Glucan with myofibrillar proteins involve hydrogen bonds and van der Waals forces. In conclusion, glycosylation can effectively improve the functional properties of proteins, contributing to the development and production of high-quality, stable, and nutritious rabbit meat products.

Revealing the deterioration mechanism in gelling properties of pork myofibrillar protein gel induced by high-temperature treatments: Perspective on the protein aggregation and conformation

The purpose of the present study was to investigate the mechanism of gel deterioration of myofibrillar proteins (MP) gels induced by high-temperature treatments based on the protein aggregation and conformation. The results showed that the gel strength and water holding capacity of MP obviously increased and then decreased as the temperature increased, reaching the maximum value at 80 °C (P < 0.05). The microstructure analysis revealed that appropriate temperature (80 °C) contributed to the formation of a more homogeneous, denser, and smoother three-dimensional mesh structure when compared other treatment temperatures, whereas excessive temperature (95 °C) resulted in the formation of heterogeneous and large protein aggregates of MP, decreasing the continuity of gel networks. This was verified by the rheological properties of MP gels. The particle size (D4,3 and D3,2) of MP obviously increased with larger clusters at excessive temperature, and the surface hydrophobicity of MP decreased (P < 0.05), which has been linked to the formation of soluble or insoluble protein aggregates. Tertiary structure and secondary structure results revealed that the proteins had a tendency to be more stretched under higher temperature treatments, which resulted in a decrease in covalent interactions and non-covalent interactions, fostering the over-aggregation of MP. Therefore, our present study indicated that the degradation of MP gels treated at high temperatures was explained by protein aggregation and conformational changes in MP.

Cyclic Continuous Glycation Enhanced Dispersibility of Myofibrillar Protein: Reaction Efficiency and Sites Modification

Reaction efficiency in glycation lacks sufficient attention, leading to the waste of process costs. Cyclic continuous glycation (CCG) is an effective approach to accelerate covalent binding between myofibrillar protein (MP) and glucose. This study elucidated that CCG promoted the exposure of reactive glycated sites in MP with full unfolding of secondary and tertiary structures. Notably, the glycation rate was significantly increased by 65.43%. Physicochemical properties indicated that MP-glucose conjugates with high graft degree exhibited favorable solubility, dispersibility, and thermal stability. Furthermore, proteomics was applied to reveal the glycated sites and products in glycoconjugates of MP. Glycation preferentially acted on the tails of the myosin heavy chain. The glucosylation modification on the head region was enhanced by CCG contributing to the inhibition of the head-head interaction. Overall, this study systematically clarifies the mechanism of CCG, providing a theoretical basis for the application of glycation in innovative meat products.

Ultrasound-enhanced covalent reaction of gliadin: the inhibition of antigenicity and its potential mechanisms

BACKGROUND

Wheat proteins can be divided into water/salt-soluble protein (albumin/globulin) and water/salt-insoluble protein (gliadins and glutenins (Glu)) according to solubility. Gliadins (Glia) are one of the major allergens in wheat. The inhibition of Glia antigenicity by conventional processing techniques was not satisfactory.

RESULTS

In this study, free radical oxidation was used to induce covalent reactions. The effects of covalent reactions by high-intensity ultrasound (HIU) of different powers was compared. The enhancement of covalent grafting effectiveness between gliadin and (-)-epigallo-catechin 3-gallate (EGCG) was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, matrix-assisted laser desorption/ionization-time-of-flight-mass spectrometry and Folin-Ciocalteu tests. HIU caused protein deconvolution and disrupted the intrastrand disulfide bonds that maintain the tertiary structure, causing a shift in the side chain structure, as proved by Fourier, fluorescence and Raman spectroscopic analysis. Comparatively, the antigenic response of the conjugates formed in the sonication environment was significantly weaker, while these conjugates were more readily hydrolyzed and less antigenic during simulated gastrointestinal fluid digestion.

CONCLUSION

HIU-enhanced free radical oxidation caused further transformation of the spatial structure of Glia, which hid or destroyed the antigenic epitope, effectively inhibiting protein antigenicity. This study widened the application of polyphenol modification in the inhibition of wheat allergens. © 2024 Society of Chemical Industry.

Proteomics analysis of the influence of proteolysis on the subsequent glycation of myofibrillar protein

Proteomics was used to study the influence of proteolysis on the glycation of myofibrillar proteins (MPs). Proteolysis by papain and proteinase K generated the highest level of amino acids (AAs) and peptides, respectively. Both the glycation degree (A value increased from 0.173 to 0.202-0.348) and speed (k value increased from 0.0099 to 0.0132-0.0145) were enhanced by proteolysis using papain and proteinase K. Proteomics analysis revealed that proteolysis largely enhanced the glycation site number in Lys, Arg and N-terminal residues (eg. Leu, Gly, Thr, Ala, Met, Ile, Phe and Val residues in myosin light chain). Proteolysis by papain preferentially acted on actin and therefore specifically increased the glycation sites from actin. Proteolysis reduced the level of aldehydes but enhanced the aromatic E-nose signals, possibly due to the combination of aldehydes with released AAs/peptides. The proteomics analysis helped to detail the relationship between proteolysis and subsequent glycation/flavour formation.

Magnetic field-driven biochemical landscape of browning abatement in goat milk using spatial-omics uncovers

Influence of magnetic field (MF) treatment on the glycation of goat milk proteins is yet to be elucidated. Proteomic and metabolomic analyses of brown goat milk samples with and without MF treatment were performed. Assessed glycation degree and structural modification of proteins explained that MF treatment dramatically down-regulated the glycation of brown goat milk protein, possibly due to the aggregation behavior induced by MF treatment, which consumed additional glycation sites as well as altered their accessibility and preference. Integrated datasets uncovered that the energy metabolism-related biological events including carbohydrate metabolism, glycerophospholipid metabolism, TCA cycle may mainly account for the browning abatement mechanism of MF. In addition, MF treatment enhanced both the quality and flavor of brown goat milk. This study suggests the feasibility of MF treatment to reduce glycation in brown goat milk for producing high-quality dairy ingredients and products.

High-temperature glycosylation modifies the molecular structure of ovalbumin to improve the freeze-thaw stability of its high internal phase emulsion

In this study, ovalbumins (OVAs) were glycosylated with fructo-oligosaccharide (FO) at different temperatures (80 °C, 100 °C, 120 °C, and 140 °C) and durations (1 h and 2 h) via wet-heating. The glycosylated OVAs (GOVAs) were characterized by the degree of glycosylation (DG), particle size, zeta potentials, and structural changes. GOVAs-stabilized high-internal-phase emulsions (HIPEs) were then prepared to compare their macro- and microstructure and freeze-thaw stability. The results showed that the DG of GOVAs increased with the increase in glycosylation temperature and the protein structure unfolded with it. Glycosylation decreased the particle size, zeta potential, and α-helical structures and increased the β-sheets and surface hydrophobicity (H₀) of GOVAs compared with unmodified OVAs. Moreover, GOVAs-stabilized HIPEs exhibited smaller particle sizes, zeta potentials, agglomeration indexes, oil loss rates, and freezing points and higher viscoelasticity, centrifugal stabilities, flocculation indexes, and freeze-thaw stabilities. Notably, HIPEs prepared by GOVAs (glycosylated higher than 120 °C) showed the least changes in macro- and microscopic appearances after freeze-thawing. These findings will provide a novel method for improving and broadening the functionalities of OVAs and potentially develop HIPEs with enhanced freeze-thaw stabilities.

Utilization of ultrasound and glycation to improve functional properties and encapsulated efficiency of proteins in anthocyanins

The purpose of this study is to explore the optimal conditions for the preparation of bovine serum albumin (BSA)/casein (CA)-dextran (DEX) conjugates by ultrasonic pretreatment combined with glycation (U-G treatment). When BSA and CA were treated with ultrasound (40% amplitude, 10 min), the grafting degree increased 10.57% and 6.05%, respectively. Structural analysis revealed that ultrasonic pretreatment changed the secondary structure, further affected functional properties of proteins. After U-G treatment, the solubility and thermal stability of BSA and CA was significantly increased, and the foaming and emulsifying capacity of proteins were also changed. Moreover, ultrasonic pretreatment and glycation exhibited a greater impact on BSA characterized with highly helical structure. Complexes fabricated by U-G-BSA/CA and carboxymethyl cellulose (CMC) exhibited protection on anthocyanins (ACNs), delaying the thermal degradation of ACNs. In conclusion, the protein conjugates treated by ultrasonic pretreatment combined with glycation have excellent functionality and are potential carrier materials.

Formation of Nε-Carboxymethyl-Lysine and Nε-Carboxyethyl-Lysine in Heated Fish Myofibrillar Proteins with Glucose: Relationship with Its Protein Structural Characterization

The formation of advanced glycation end products (AGEs), including N^ε-carboxymethyl-lysine (CML) and N^ε-carboxyethyl-lysine (CEL), in a fish myofibrillar protein and glucose (MPG) model system at 80 °C and 98 °C for up to 45 min of heating were investigated. The characterization of protein structures, including their particle size, ζ-potential, total sulfhydryl (T-SH), surface hydrophobicity (H₀), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared spectroscopy (FTIR), were also analyzed. It was found that the covalent binding of glucose and myofibrillar protein at 98 °C promoted protein aggregation when compared with the fish myofibrillar protein (MP) heated alone, and this aggregation was associated with the formation of disulfide bonds between myofibrillar proteins. Furthermore, the rapid increase of CEL level with the initial heating at 98 °C was related to the unfolding of fish myofibrillar protein caused by thermal treatment. Finally, correlation analysis indicated that the formation of CEL and CML had a significantly negative correlation with T-SH content (r = -0.68 and r = -0.86, p ≤ 0.011) and particle size (r = -0.87 and r = -0.67, p ≤ 0.012), but was weakly correlated with α-Helix, β-Sheet and H₀ (r² ≤ 0.28, p > 0.05) during thermal treatment. Overall, these findings provide new insights into the formation of AGEs in fish products based on changes of protein structure.

Improved water solubility of myofibrillar proteins by ultrasound combined with glycation: A study of myosin molecular behavior

The poor water solubility of myofibrillar proteins (MPs) limits their application in food industry, and is directly related to the molecular behavior associated with myosin assembly into filaments. This study aims to explore the effect of high-intensity ultrasound (HIU) combined with nonenzymatic glycation on the solubility, structural characteristics, and filament-forming behavior of MPs in low ionic strength media. The results showed that the HIU (200-400 W) application could promote the subsequent glycation reaction between MPs and dextran (DX) and interfere with the electrostatic balance between myosin rods, suppressing the formation of filamentous myosin polymers. Glycated MPs pretreated by 400 W HIU had the highest solubility, which corresponded to the smallest particle size, highest zeta potential, and optimum storage stability (P < 0.05). Structure analysis and microscopic morphology observations suggested that the loss of the MP superhelix and the depolymerization of filamentous polymers were the main mechanisms for MP solubilization. In conclusion, HIU combined with glycation can effectively improve the water solubility of MPs by destroying or suppressing the assembly of myosin molecules.

Improving the solubility of myofibrillar proteins in water by destroying and suppressing myosin molecular assembly via glycation

Filamentous myosin is a self-assembling polymer that prevents myofibrillar proteins (MPs) from functioning in low ionic strength media. This study was aimed at investigating if glycation has the potential to improve the solubility of MPs in water. MPs were conjugated with monosaccharides, oligosaccharides, and polysaccharides under wet reaction conditions at 37 °C. The conjugation was verified by SDS-PAGE, FT-IR and amino acid analyses. MPs conjugated with dextran (DX) exhibited a higher solubility and dispersion stability in water, which corresponded to smaller particle size and more uniform distribution (P < 0.05). According to secondary and tertiary structure analyses, the loss of α-helix structures and unfolding of the MPs appear to be the main reasons for MP solubilization. Additionally, according to the zeta-potential, confocal laser scanning microscopy, and atomic force microscopy observation results, glycation can provide electrostatic repulsion or steric hindrance to disintegrate existing filamentous myosin aggregates and inhibit further self-assembly behavior.

Formation of advanced glycation end products by novel food processing technologies: A review

Advanced glycation end products (AGEs) are a diverse group of compounds formed endogenously and exogenously due to non-enzymatic glycation of proteins and lipids. Although the effects of heating on AGE concentrations in foods are known, few studies have been published addressing the effects of new processing technologies on AGE formation. This work focuses on the current scientific knowledge about the impacts of novel technologies on AGE formation in food products. Most studies do not measure AGE content directly, evaluating only products of the Maillard reaction. Moreover, these studies do not compare distinct operational conditions associated with novel technologies. This lack of information impacts negatively the establishment of process-composition relationships for foods with safe AGE dietary intakes. Overall, the outcomes of this review suggest that the use of novel technologies is a promising alternative to produce food products with a lower AGE content.

New insights into the ultrasound impact on covalent reactions of myofibrillar protein

In this work, two different covalent reactions, namely, alkaline reaction and free radical oxidation, were selected to compare the difference in the strengthening effects of ultrasound treatment (UDT). The grafting effects were verified by protein electrophoresis and bound gallic acid (GA) assay. Furthermore, non-covalent interactions between myofibrillar protein (MPN) aggregates were destroyed by UDT, as proved by the lower particle sizes and higher ζ-potential. Comparatively, the results from tertiary structure index and circular dichroism revealed UDT-assisted free radical oxidation could lead to better conjugates with greater structural properties. The atomic force microscope (AFME) and protein flexibility showed that MPNs appeared to display as irregular spherical particles after alkaline reaction, however, maintained fibrous structure during the free radical oxidation. Consequently, the combination of UDT and free radical oxidation were more effectively for strengthening the influence of acoustic cavitation on MPNs, of which mechanism was the changes in viscosity properties, microstructure and acoustic cavitation radicals.

Ultrasonic Synthesis of Nanochitosan and Its Size Effects on Turbidity Removal and Dealkalization in Wastewater Treatment

A detailed study on the synthesis of chitosan nanoparticles under ultrasonication is reported in this paper. By using this simple technique, chitosan particles in nanometer range can be easily prepared without using any harmful and expensive chemicals. The results show that increasing the ultrasonic irradiation time and ultrasonic wave amplitude are the key factors for producing discrete chitosan nanoparticles with narrow particle size distribution. The resulting nanoparticles show superior turbidity removal efficiency (75.4%) and dealkalization (58.3%) in wastewater treatment than the bulk chitosan solid (35.4% and 11.1%, respectively), thus offering an eco-friendly and promising approach for treating wastewater via the coagulation/flocculation process.

Comparison of two kinds of peroxyl radical pretreatment at chicken myofibrillar proteins glycation on the formation of Nε-carboxymethyllysine and Nε-carboxyethyllysine

During meat processing, two typical advanced glycation end products (AGEs), N^ε-carboxymethyllysine (CML) and N^ε-carboxyethyllysine (CEL), are generated by free radical induction. However, the impact of peroxyl radicals on myofibrillar proteins (MPs) glycosylation and CML and CEL formation is scarcely reported. In this study, two peroxyl radicals called ROO· and LOO· derived from AAPH (2,2'-azobis (2-methylpropionamidine) dihydrochloride) and linoleic acid were exposed prior to the Maillard reaction (glucosamine incubation at 37 °C for 24 h). Levels of AGEs (CML/CEL), protein oxidation (sulfhydryl/carbonyl), free amino group, surface hydrophobicity, zeta potential, particle size, intrinsic fluorescence intensity and secondary structure were determined. Together with Pearson's correlation, the assumption that free radicals promote MPs oxidation and glycation, alter the aggregation behavior and structure modification, leading to AGEs promotion has been built. In addition, the effect of dose-dependency of peroxyl radical on AGEs has also been established with different effects of peroxyl radical induction.

Review of the formation and influencing factors of food-derived glycated lipids

Glycated lipids are formed by a Maillard reaction between the aldehyde group of a reducing sugar with the free amino group of an amino-lipid. The formation and accumulation of glycated lipids are closely related to the prognosis of diabetes, vascular disease, and cancer. However, it is not clear whether food-derived glycated lipids pose a direct threat to the human body. In this review, potentially harmful effect, distribution, formation environment and mechanism, and determination and inhibitory methods of glycated lipids are presented. Future research directions for the study of food-derived glycated lipids include: (1) understanding their digestion, absorption, and metabolism in the human body; (2) expanding the available database for associated risk assessment; (3) relating their formation mechanism to food production processes; (4) revealing the formation mechanism of food-derived glycated lipids; (5) developing rapid, reliable, and inexpensive determination methods for the compounds in different foods; and (6) seeking effective inhibitors. This review will contribute to the final control of food-derived glycated lipids.

Ultrasonic pretreatment enhanced the glycation of ovotransferrin and improved its antibacterial activity

This study aims to evaluate the effect of ultrasonic pretreatment combined with glycation on the structural characteristics and antibacterial activity of ovotransferrin (OVT). Firstly, OVT (purity >90%) was isolated from egg white with a simple and efficient method. After the treatment of ultrasound and glycation, the browning degree of OVT increased with the rising power of ultrasound, while the number of free amino groups obviously decreased to 25.4%. Various spectrum detection showed that the structures of OVT have changed significantly, indicating the tertiary structure became more flexible and looser. The minimal inhibitory concentration of ultrasound glycated OVT were 25.0 and 32.1 μmol/L for E. coli and S. aureus, respectively. In summary, ultrasound-assisted glycation is an effective technique to improve the biological activity of OVT.

Glycation from α-dicarbonyl compounds has different effects on the heat-induced aggregation of bovine serum albumin and β-casein

α-Dicarbonyl compounds are generated in large amounts during heat treatment in food production. This work compared the influence of glycation by α-dicarbonyl on the hydrothermal aggregation of bovine serum albumin (BSA) and of β-casein (β-CN). Glycation by α-dicarbonyl compounds was found to be more efficient than glycation by glucose in reducing the free amino groups, surface hydrophobicity and isoelectric point of BSA, thus greatly inhibited the hydrothermal aggregation of BSA. In addition, glycation by α-dicarbonyl greatly transformed the rigid BSA aggregates into flexible structures, based on analysis by fluorescence spectrum, transmission electron microscope and small-angle X-ray scattering. In contrast, both the aggregation process and aggregates conformation of β-CN were found to be minimally affected by glycation, possibly due to the intrinsic disorder of β-CN. This work highlights the substantial influences of α-dicarbonyl on dietary proteins during heat treatment depending on the protein structural characteristics.